Motor fuel blend containing hydrogenated heavy cracked naphtha



United States Patent 3,330,758 MOTOR FUEL BLEND CONTAINING HYDRO- GENATED HEAVY CRACKED NAPHTHA Charles F. Simpson, Monrovia, Califi, assignor to Atlantic Richfield Company, a corporation of Pennsylvania No Drawing. Filed July 27, 1964, Ser. No. 385,456 1 Claim. (Cl. 208-17) The present invention relates to a treating method for improving the engine cleanliness characteristics of gasoline blending stocks and is a continuation-in-part of my application Ser. No. 97,415, filed Mar. 22, 1961, now abandoned. More particularly, my invention relates to a method for treating hydrogenated heavy catalytic cracked naphtha to improve its odor and decrease its engine sludge and varnish forming tendencies.

Catalytic cracking processes produce generally a cycle gas 'oil, cracked gases, and a cracked gasoline product which usually has a relatively broad boiling range, for example, from about 100-425 Fahrenheit. This cracked gasoline product as well as the lighter products of visbreaking processes, may be fractionated into several cuts which may be subsequently treated and blended to produce various gasoline blending components, the highest boiling of which is called heavy catalytic naphtha or heavy cracked naphtha. Economically, it is desirable to utilize each of these latter cuts for gasoline blending with minimum subsequent treatment. It has been found, however, that the heavy catalytic naphtha stock which is quite often hydrogenated before blending is the least desirable as a gasoline blending component from the standpoint of resulting engine cleanliness, which generally includes rust, varnish, and sludge formation, ring sticking, ring plugging, valve seat deposits, and valve stem deposits.

Prior attempts to improve the engine cleanliness characteristics of hydrogenated heavy cracked naphtha include end point cutting and increasing the severity of the hy drogenation treatment, neither of which have been effective to reduce the marked varnish-forming characteristics of this heavy catalytic naphtha stock.

It is, therefore, an object of the present invention to provide a method for treating heavy cracked naphtha to improve the engine cleanliness characteristics of said naphtha.

It is also an object of my present invention to provide a method for treating heavy cracked naphtha to improve the engine cleanliness characteristics of said naphtha whereby subsequent fractionation is not required. Other objects and a more complete understanding of my invention will become apparent from the following description, examples and the appended claims.

Briefly stated, my invention accomplishes the foregoing objects by providing a treating process whereby the heavy cracked naphtha is subjected to hydrogenation and subsequently a dilute acid treatment. In accordance with my present invention, I have discovered that the poor engine cleanliness characteristics of the gasoline blending component, heavy cracked naphtha, can be greatly improved to yield a naphtha with excellent engine cleanliness characteristics by subjecting a caustic pro-washed heavy cracked naphtha to a hydrogenation treatment followed by admixing the hydrogenated product with water diluted sulfuric acid and subsequently neutralizing.

A suitable caustic pre-wash is accomplished by treating the heavy cracked naphtha with -40 Baum aqueous sodium or potassium hydroxide at room temperature.

The hydrogenation treatment given the heavy cracked naphtha is preferably a mild treatment primarily to stabilize the heavy naphtha for storage and thereby remove certain undesirable constituents such as diolefins and cycloolefins which, if present, apparently alkylate or polymen'ze during the subsequent dilute acid treatment to increase the end point of the treated stock and form undesir able engine gums and sludges. It is desirable that the hydrogenation be a mild treatment to minimize hydrogenation costs and also maintain the octant rating of the hydrogenated product which rating would be reduced by severe hydrogenation due to saturation of high octant rating olefins. Preferably the bromine number of the heavy naphtha should not be lowered more than 5 by the hydrogenation treatment. The required severity 'of the hydrogenation treatment can be effectively reduced by removal of phenols or cresylic acids prior to hydrogenation as by subjecting the heavy catalytic naphtha to an aqueous caustic pre-wash as previously set forth.

The hydrogenation treatment may be performed in a catalytic hydrogenation unit, preferably one using a cobalt molybdate catalyst supported on alumina or silicaalumina, although any of the catalysts conventionally employed in the hydrogenation of petroleum hydrocarbons can be utilized in accordance with my process. Examples of suitable catalytic ingredients are molybdenum, tungsten, vanadium, chromium, cobalt, nickel, iron and tin and their oxides or sulfides. Mixtures of these materials or compounds of two or more of the oxides or sulfides can be employed. For example, mixtures of compounds of the iron group metal oxides with oxides of Group VIleft column of the Periodic Table constitute quite satisfactory catalysts. Examples of such mixtures of the compounds are nickel molybdate, tungstate, or chromate or mixtures of nickel oxide with molybdenum, tungsten, or chromium oxide. 'Ihese catalytic ingredients are generally employed while disposed upon a suitable carrier of the solid refractory type according to refinery practices well known to those skilled in the art.

In addition to the possible variations in the catalyst employed several other operating conditions utilized in the hydrogenation treatment process can be varied in accordance with the hydrogenation step of my invention. For example the hydrogenation can be carried out at a temperature within the range of 500 to 800 Fahrenheit, at a pressure within the range 'of 200 to 1000 p.s.i.g., at a weight hourly space velocity of from 1 to 12 and at a hydrogen rate of from 500 to 5000 standard cubic feet per barrel of heavy catalytic naphtha feed. As an example of typical operating conditions one such hydrogenation treatment is carried out between 550 to 650 Fahrenheit at approximately 600 p.s.i.g., at a weight hourly space velocity of 6 and a hydrogen rate of approximately 1000 cubic feet per barrel.

The dilute acid treatment following the hydrogenation step is preferably carried out in any suitable continuous acid treating equipment, for example a jet of dilute sulfuric acid may be introduced into the heavy naphtha stream and comingled with the naphtha and the acid-naphtha mixture subsequently pumped to electrostatic precipitators which can be employed to rapidly separate the acid from the naphtha and thereby minimize the amount of caustic solution which is subsequently required to neutralize the naphtha after the acid treatment. The dilute acid treatment can be performed at room temperature and atmospheric pressure.

Several typical gasoline blending components were evaluated for engine cleanliness characteristics using a laboratory varnish test procedure including engine varnish test rating, ASTM existent gum test and the 16 hour accelerated varnish gum test run with an iron strip. The results of these evaluations indicate the inferiority of the hydrogenated heavy catalytic cracked naphtha stock. The engine test procedure consisted of operating a six cylinder Chevrolet engine on an engine dynamometer with 4 quarts of a reference oil and with the fuel to be tested for a period of forty hours under controlled speed, load and temperature. Upon completion the engine was disassembled and rated for varnish formation on piston skirts, cylinder walls and the overall engine. The engine was also rated for overall sludge, valve stem and valve tulip deposits, intake port deposits, corrosion, rust, and stuck, and tight piston rings. An overall (total) rating of 85 based upon a CRC numerical rating system is acceptable if the piston skirt and/or cylinder wall varnish rating is equal to or higher than 7.5 (out of a possible clean rating of Blending components having accelerated varnish gum (washed) run with an iron strip, of 9 or less, are satisfactory from the engine cleanliness standpoint. While We have used gum tests as an indication of engine cleanliness in a series of treats, We must not use gum tests as a substitute for 40E runs, in blends containing different constituents.

Examples 1-25 A heavy cracked naphtha having an API gravity of 386 and an ASTM boiling range of 246-420" F. was admixed with one volume of 33 Baum aqueous caustic soda per ten volumes of catalytic naphtha at room temperature. The caustic treated naphtha was then hydrogenated in an upflow type reactor using a cobalt molybdate.catalyst (Nalco 471) supported on silica-alumina at a reactor outlet temperature of 653 F. (reactor temperature rise of 44 F.) and a reactor inlet pressure of 557 p.s.i.g. (reactor pressure drop of 4.6 psi.) The weight hourly space velocity, on a liquid feed basis, was 10.29 and the hydrogen rate 1234 cubic feet (total gas) per barrel of feed. The hydrogenated product had the following properties:

.4 API gravity 39.0 ASTM distillation, F.:

Initial boiling point 244 10% 289 336 388 EP 426 ASTM gum-mg./ ml.:

Before solvent wash 3.2 After solvent wash 3.0 16 hour accelerated gum:

Before solvent wash 16.0 After solvent wash 15.8 Research octane rating: F1+ml. TEL 95.7

The hydrogenated heavy cracked naphtha product was then treated with various sulfuric acids as designated, at various dilutions and acid rates in a glass-lined Pfaudler kettle, by intermixing the acid with about 50 gallons of the naphtha for one to one and a half hours after which the acid and naphtha mixture was left for one hour to settle. The lower layer (acid) was removed and the treated naphtha washed twice with water and then with sodium carbonate-The acid treated naphtha was then used as a component in a fuel which was tested in accordance with the above test for engine cleanliness characteristics. The results of the tests made on these acid treated naphtha stocks are shown in Table I. The acid treated hydrogenated heavy naphtha was blended as 60% of the motor fuel tested with the remaining components being 35% 335 Fahrenheit E.P. straight run gasoline and 5% n-butane.

Table II shows comparative properties of the heavy cracked naphtha stock as tested.

TABLE I.HYDROGENATED PRODUCT ImROVEMENT BY ACID TREATING Varnish Test Acid Treats Rating 1 ASTM Gum, rug/100 ml.

Nitrogen, p.p.m.

Research 0ctane, F-1+3 ml. TEL

Gum, mg./l00

ml. ASTM Dist.

0 dor Pisotn Skirt or Cylinder Wall Cone, Percent Acid Type Total After Wash 3 Before After Treating Total Basic oownhthcnoocco D d Sludge From Treat #10 Used Acid Sludge From Treat #5 1 On Blended Fuel Used for Engine Run. 9 lfi-hr. Accelerated Varnish Gum, run with an Iron Strip. Gums were washed with hexane.

TABLE II.FUEL INSPECTION DATA Hydrotreated Heavy Cracked Gasoline Reactor Temp.

Hydrogenation 652 F. 750 F. 750 F. 652 F. 660 F. Unit Feed Unit Operation Feed Rate {b.ld.)

Boiling Range Full 400 EP 375 EP Full 400 EP 375 EP Full Full Full Full Full Full Range Cut Cut Range Cut Out Range Range 1 Range 2 Range Range Range 4 Untreated Inspections: Gravity,

API 47. 4 48. 49. 1 47. 0 47. 7 49. 2 47. 8 47. 0 47. 2 46. 6 46. 5 46. 5 99 102 98 105 97 102 100 99 103 95 97 95 141 148 152 164 161 152 151 152 148 150 147 186 194 195 204 184 203 188 191 193 193 195 187 238 244 244 250 241 240 237 247 247 249 251 242 307 305 294 312 307 294 307 313 306 305 309 303 390 371 340 387 373 337 397 390 383 382 387 389 431 411 376 422 409 375 442 425 418 416 425 450 98. 0 98.0 98.5 97. 5 98. 0 97. 5 89. 0 98. 0 98. 0 98. 0 98 98 7.2 6.6 6.5 6.5 6.7 5.7 6.7 6.8 6.6 6.0 7.4 7.5 3.0 1.8 1.2 2.4 1.4 1.2 1.4 2.6 2.4 3 8 3.8 25.4 2.4 1.4 1.0 1.6 1.4 0.6 0.6 1.4 1.2 3.0 1.2 6. 8 3. 6 4.1 5. 2 2. 8 2. 8 3.0 2.6 3. 8 4. 2 27. 2 27. 6 0. 02 0. 09 0. 12 0. 04 0. 04 0. 03 0. 06 0. 08 0. 11 0. 117 0. 24 0. 25 244 277 215 190 413 87 69 8. 7 16. 8 8. 5 425 Neg Neg Neg. Neg Neg. Neg Neg Neg. Neg. Neg Neg. Neg percent 0. 001 0.001 0.001 0. 001 0. 001 0. 001 0 001 0. 001 0.001 0. 001 O. 001 0. 001 Peroxide N0 0. 01 0. 01 0. 1 0.1 0 01 D l 0.1 0. 1 1. 1 0. l V 0.1 0.1 Rust Rating D E C D 13-!- C D E B+ D B+ FIA, V01. percent:

saturates 61. 9 58. 6 56. 7 62. 8 62. 7 64. 1 68. 1 57. 6 59. 4 57. 9 55. 2 55. 0 OlefinS 7. 3 10.9 13. 1 5. 5 6. 1 7. 2 2. 4 10. 9 9. 3 9.6 12. 3 12.7 Aromatics 30. 8 30. 5 30. 2 31. 7 31. 2 28. 7 29. 5 31. 5 31. 3 32. 5 32. 5 32. 3

l Treated with 15.1 lbs. of 80% Sulfuric Acid. 2 Treated with 11.1 lbs. of 60% Sulfuric Acid. 3 Treated with 2.8 lbs. of 60% Sulfuric Acid.

The results set forth in Table I clearly show that the heavy hydrogenated cracked naphtha without acid treatment is not acceptable from an engine cleanliness stand-' point since the overall or total rating is 67 which is below the acceptable rating of 85. The gum and the nitrogen content were high and the odor was bad. It may also be concluded from these data that treatment of the hydrogenated heavy cracked naphtha with concentrated acid was not satisfactory since the end point of the product was raised excessively which increase would requireredistil-ling before blending with motor fuel. These data show that a dilute acid treatment using an acid solution of 4 Treated with 11.1 lbs. of 60% Sulfuric Acid. NOTE-A11 stocks blended with 335 EP straight run and normal butane.

observed treating with acid which had been substantially diluted with water improved the odor of the hydrogenated product.

The research octane degradation due to treating with the 60% and strength acid was 0.5 of a number or less at the 3 milliliter of tetraethyl lead level.

Examples 26-30 A portion of the heavy cracked naphtha before hydrogenation was treated with dilute acid and compared with the same product after being hydrogenated to determine whether hydrogenation prior to dilute acid treatment is essential to the improvement of engine cleanliness :by dilute acid treatment according to my present invention. The results as tabulated in Table 111 indicate that the dilute acid treatment is not eifective in improving the engine cleanliness characteristics of the heavy cracked naphtha stock unless the stock has been hydrogenated prior to the dilute acid treatment. A possible explanation for this phenomenon is that the hydrogenation treatment, even though mild, removes the diolefins and cyclic aromatics which would tend to alkylate and polymerize in 7 8 the acid treatment if not previously removed, thus formdilute acid treatment on storage stability. An aluminum ing undesirable engine deposits. beaker-brass float test was used to predict gum forming TABLE IIL-EFFECT OF ACID TREATING THE HEAVY CRACKED NAPHTHA BEFORE AND AFTER HYDROGENATION Hydrogenation Unit Product Hydrogelr iatgon Unit Example No 26 27 28 29 30 Reactor Temperature, T 652 660 660 Fresh Acid:

Strength, percent 80 60 60 60 15.1 11.1 2.8 11.1 235 235 235 235 235 8.0 8. 7 6. 5 4. 5 4.0 7. 5 7. 6. 5. 0 3. 0 10.0 v 0 7. 0 10.0 10.0 10.0 10.0 7. 0 9. 0 9. 0 9.0 8.7 6.5 7.0 9.0 Intake Valve Tulip. 9. 0 9. 0 7. 5 8. 7 6.0 Intake Valve Port- 9. 0 8. 0 4. 8 3. 5 8.0 Corrosion 9. 0 9. 0 8. 5 9. 0 9. 0 Average Sludge 7. 7 7. 5 7. 7 6. 4 6.1 Average Varnish-. 7. 6 7. 7 6. 8 6. 2 5. 6 Total Rating (100 Perfect).-." 86.8 85. 6 68. 9 69. 3 69. 7

Varnish (10 Perfect):

Rocker Arm Cover 7. 8 7. 3 7. 0 6. 5 6.0 Push Rod Cover 7. 5 8.0 7. 0 7. 0 8.0 Timing Gear Cover... 7.5 7.0 7. 0 6.0 6.0 Crankcase Pan 7. 0 8.0 7. 0 8.0 6. 5 Piston Skirt 8.0 8. 7 6. 5 4. 5 4.0 Cylinder Wall. 7. 5 7. 0 6. 5 5. 0 3. 0 Average Varnish 7. 6 7. 7 6. 8 6. 2 5. 6

Total Varnish Rating (60 Periect) 43 3 46 0 41.0 39 0 33 5 Sludge (10 Perfect):

Rocker Arm Cover 7. 5 8. 4 8. 7 7. 0 7. 0 Push Rod Cover-.... 8.0 6.0 8.0 4. 2 5. 5 Timing Gear Cover 6. 5 6.0 6.0 4.0 5. 0 Crankcase Pan-.. 7. 5 8. 5 6. 0 6.0 6.0 Top Deck 8. 0 7. 5 8.0 8. 0 5. 0 Rocker Arm Assembly. 9. 0 8.0 9. 0 8. 0 7. 0 Oil Screen 7. 5 8. 5 8. 5 8.0 7. 0 Average Sludge Rating 7. 7 7. 5 7. 7 6. 4 6.1

Total Sludge Rating (70 Perfeet) 54 0 52 9 54.2 2 43 0 45 characteristics of these stocks in carburetors during peri- Examples 31-34 ods of extended storage. The results show that acid treat- Table IV shows the results of a simulated carburetor ing the hydrogenated product and running either straight evaporation test run on heavy hydrogenated cracked or in -50 blends with reformate increased the ability naphtha with and without dilute acid treatment accordof the dilute acid treated product to resist gum formation ing to the present invention to determine the effect of the 50 during prolonged storage in the presence of brass.

TABLE IV.EFFECT OF ACID TREATING ON STORAGE STABILITY (SIMULATED CARBURETOR EVAPORATION TEST) Example No.

Fuel

Heavy Hydro Heavy Hydro Treated 1 50% Heavy Hydro] 50% Heavy 1 Hydro 50% Reiormate Treated/50% Reformate Cu Pickup, p.p.m.:

Cu Before Exposure .05.... .05.

011 After Exposure 1.75 .05 Deposit Solubility Illn-Peutane .9820 gr .1630 gt... .111 gr.

30% Venzeue. 70% n-Hexane. 5.1775. .0792.-. .0330.

Acetone 1.6569" 0835-. .0419.

Acetone Insoluble. .2530 .0781 .3077 .0062.

Deposit Appearance Heavy, stic y deposit Small amount Heavy, sticky deposit Small amount of light on bottom sides, and sticky deposit. on bottom, sides, sticky deposit on float. Slightly corro- Slightly glazed. and float. Corrosive. bottom. Sides and sive. Slightly corrosive. float slightly glazed.

. Slightly oxidized.

Odor after Evaporation Oxidized Slighty Oxidized Oxidized Slightly Oxidized.

1 Treat consisted of 10# of H SOr/bbl.

NOTE. All Samples with 3 ml. TEL.

Although I have described the present invention with a certain degree of particularity it is to be understood that various changes and alterations may be made in the details set forth herein without departing from the spirit of my invention and that my invention is to be given the full scope of the appended claim.

I claim:

A motor fuel comprising 60% of a heavy catalytic naphtha, 35% of a 335 F. end point straight run gasoline, and of normal butane, said heavy catalytic naphtha boiling in the range of about 250 to 450 F. and being obtained 'by fractionation of cracked products produced by catalytic cracking and having had its engine cleanliness properties improved by admixing it With 15- 40 Baum aqueous sodium hydroxide whereby the content of phenols in said heavy catalytic naphtha is reduced, catalytically hydrogenating said heavy naphtha with molecular hydrogen over a cobalt molybdate catalyst at a temperature within the range of 500 to 750 F., a pressure within the range of 200 to 1000 p.s.i.g. and at a weight hourly space velocity within the range of from 1 to 12 and at a hydrogen rate of 500 to 5000 standard cubic feet per barrel of naphtha, thereafter treating said catalytic naphtha with an aqueous solution of sulfuric acid of about 60 to 80 weight percent acid, separating the acid from said catalytic naphtha, and neutralizing said separated catalytic naphtha to stabilize said naphtha and reduce its accelerated varnish gum content to less than 9 mg./ 100 m1. naphtha and hold the end point of said naphtha to a level at which said treated naphtha is suitable for use as a motor fuel blending stock.

References Cited UNITED STATES PATENTS 1,658,171 2/ 1928 McMichael 208-256 1,851,580 3/1932 Howard 209-98 2,002,902 5/1935 Martin et al. 208-255 2,015,703 10/ 1935 Black et al. 208-256 2,692,226 10/ 1954 Smith 208-271 2,865,849 12/1958 Van Loom et al 208-212 2,877,172 3/1959 Morbeck et al. 2 8-97 2,893,954 7/1959 Ten Have et a1 208-224 2,984,617 5/1961 De Chellis et al 208-211 3,039,957 6/1962 Robbins et al. 208-211 3,126,331 3/1964 Landis et al. 208-240 OTHER REFERENCES Gruse et al., Chemical Technology of Petroleum, 1960,

TP 690 G 76 c. s, McGraW-Hill, New York, N.Y.,

Chapter 1, Sec. II. 5, especially pgs. -69.

Kalichevsky et al., Petroleum Refining With Chemicals,

1956, TP 690 K 27 C. 4; Elsevier Pub. Co., N.Y.C., N.Y.,

pgs. 141144.

DELBERT E. GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, Examin r.

S. P. JONES, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,330,758 July 11, 1967 Charles F. Simpson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, lines 5 and 7, for "octant", each occurrence, read octane columns 3 and 4, TABLE I, in the heading to the sixth column, for "Pisotn" read Piston columns 5 and 6, TABLE II, eighth column, line 9 thereof, for "89.0" read 98.0 columns 7 and 8, TABLE III, fourth column, line 15, for "68.9" read 68.8 TABLE IV, column 1, line 6 thereof, for "30% Venzene" read 30% Benzene Signed and sealed this 20th day of August 1968.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

